The present disclosure relates to a recording medium storage cassette used in an image forming apparatus such as a digital copier or a laser printer, for storing sheets of recording media, and to the image forming apparatus including the recording medium storage cassette.
Conventionally, there are widely used sheet feed cassettes (recording medium storage cassettes), which store a plurality of stacked sheets of paper (recording media) and feed the paper sheets one by one separately to an image forming portions of an image forming apparatus main body in accordance with image forming operation.
There is known a paper sheet cassette (sheet feed cassette) including a sheet stack tray on which paper sheets are stacked, a pressure spring under the sheet stack tray, and a paper sheet rear end guide (rear end cursor) for aligning rear ends of the paper sheets. The sheet stack tray is configured to be swingable so that its part on a downstream side in a paper sheet conveying direction can move up and down by the pressure spring. When the sheet stack tray moves upward by the pressure spring, the paper sheets stacked in the paper sheet cassette are pressed by a predetermined pressure to a feed roller (pickup roller) disposed on an apparatus main body side, so as to be fed.
The paper sheet rear end guide is configured to be movable in the paper sheet conveying direction along a guide groove formed on a bottom surface of the paper sheet cassette. In addition, the paper sheet rear end guide is provided with an auxiliary guide plate (abutting portion) for pressing the paper sheet rear ends toward the downstream side in the paper sheet conveying direction.
As the number of paper sheets in the paper sheet cassette becomes small, a slope of the sheet stack tray is increased so that a front end of the paper sheet slides backward. As a result, a nip state of the feed roller becomes unstable so that a paper feed error is apt to occur. Therefore, in this paper sheet cassette, there is disposed the auxiliary guide plate for pressing the paper sheet rear ends toward the downstream side in the paper sheet conveying direction in the paper sheet rear end guide. Thus, the paper sheets are moved toward the downstream side in the paper sheet conveying direction so as to suppress the paper feed error by stabilizing the nip state.
In addition, there is known a sheet feed cassette including a paper sheet case (cassette base) for housing paper sheets, a biasing plate (sheet stack tray) on which the paper sheets are stacked, a coil spring disposed under the biasing plate, and a regulating plate (cursor) for aligning ends of the paper sheets. The regulating plate is configured to be movable in the paper sheet conveying direction along a guide groove (rack) formed on a bottom surface of the paper sheet case. In addition, the regulating plate is provided with a stopper plate (lock portion) having an engaging portion (protrusion) that engages with the guide groove. The engagement between the engaging portion and the guide groove is released when the stopper plate is biased in a predetermined direction.
It is an object of the present disclosure to provide a recording medium storage cassette and an image forming apparatus including the same, which can suppress a paper feed error and suppress release of engagement of the rear end cursor with the cassette base.